Measuring method of a magnetic head and measuring apparatus thereof

ABSTRACT

Measuring method of a magnetic head includes (a) placing the magnetic head at normal position, defining a first direction parallel to an air bearing surface and two shielding layers of the magnetic head, and defining a second direction perpendicular to the first direction; (b) tilting the magnetic head at an angle to the second direction, applying a plurality of first magnetic fields with different intensities in the first direction, and measuring out a first output parameter curve; (c) repeating the step (b) with different angles and measuring out a plurality of first output parameter curves; (d) calculating a plurality of pinned direction tilt ratios that a pinned direction of a pinned layer of the magnetic head tilts towards the second direction according to the parameter curves; and (e) calculating a pinned direction tilt angle that the pinned direction tilts towards the second direction according to the pinned direction tilting ratios.

FIELD OF THE INVENTION

The present invention relates to a measuring method of a magnetic headand a measuring apparatus thereof, more particularly to a measuringmethod of pinned direction tilt angle of a pinned layer in the magnetichead, and a measuring method of magnetization direction tilting angle ofa free layer in the magnetic head and the apparatus thereof.

BACKGROUND OF THE INVENTION

Hard disk drive incorporating rotating magnetic disks is commonly usedfor storing data in the magnetic media formed on the disk surfaces, anda movable head are generally used to read data from and write date intotracks on the disk surfaces.

A conventional magnetic head for a slider typically includes a readportion for reading data from the disk, and a write portion for writingdata into the disk. Presently, magnetoresistive (MR) sensor is used as akind of popular read sensor because of its better capability to readdata from disk surface at a greater track and linear densities thantraditional film inductive slider. Thus, the read portion of themagnetic head is generally formed by a MR read head, such as CurrentPerpendicular to Plane (CPP), Current In Plane (CIP), tunnelmagnetoresistive (TMR), giant magnetoresistive (GMR), or anisotropicmagnetoresistive (AMR) read heads.

For example, FIG. 1 shows a conventional magnetic head 200 including aCPP-TMR read head 210 for reading data from the disk and a write head220 for writing data into the disk. The magnetic head 200 includes asubstrate body 201, an air bearing surface (ABS) 202 and a bottomsurface (not shown) opposite to the ABS 202, a trailing edge 203 and aleading edge (not shown) opposite each other. The ABS 202 is processedso as to an appropriate flying height. And the read head 210 and thewrite head 220 are provided on the trailing edge 203.

As shown in FIG. 2 a, the read head 210 includes a substrate layer 214,two shielding layers 211, 212, and a MR element (not labeled) sandwichedtherebetween. As illustrated, the MR element is a standard and normal MRelement and includes a pinning layer (or an antiferromagnetic (AFM)layer) 236, two synthetic pinned layers 231, 234, a tunnel barrier layer235, a free layer 237, and a cap layer 232. The read head 210 furtherincludes a pair of hard magnet layers 238 placed at two sides of the MRelement on the buffer layer 216 for longitudinally biasing themagnetization of the free layer 237, and an insulating layer 239 forseparating and isolating the hard magnet layer 238 from the free layer237 and the other layers of the MR element.

Referring to FIG. 2 a again, concretely, the pair of hard magnet layers238 has a magnetic direction, indicated by arrow 258, the magneticdirection 258 orients generally parallel to the ABS 202 (shown in FIG.1). The pinned layer 231 has a pinned direction 254 for preventing fromrotation in the presence of applied magnetic fields in the desired rangeof interest. Desired by manufacturer and the customers, the pinneddirection 254 of the pinned layer 231 should be oriented perpendicularto the ABS 202 to achieve the best function, which is called normalpinned direction or standard pinned direction. The free layer 237contains a ferromagnetic substance and has a magnetization direction 256that changes in responds to an external magnetic field. Also desired,it's the best that the magnetization direction 256 of the free layer 237orients parallel to the ABS 15 in the absence of an applied externalmagnetic field, under this case the magnetization direction is callednormal magnetization direction or standard magnetization direction. Inother words, ideally, the normal pinned direction 254 of the pinnedlayer 231 is perpendicular to the normal magnetization direction 256 ofthe free layer 237.

However, in the practical application of a magnetic head product, theactual pinned direction 254′ of the pinned layer 231 always has anoffset to the normal pinned direction 254 for certain factors, and theactual magnetization 256′ of the free layer 237 also has an offset tothe normal magnetization direction 256, as shown in FIG. 2 b, forexample. As illustrated, the actual pinned direction 254′ tilts from thenormal pinned direction 254 at an angle of θ1, and the actualmagnetization direction 256′ tilts from the actual pinned direction 254′at an angle of θ2. By all appearances, the above-mentioned tilt anglesare not desired since it will bring unstable performance. However, thereis still no solution for the manufacturers to accurately measure out theactual tilt angles θ1, θ2 yet. Thus it's hard for the technical personsto test the instability of the pinned layer and free layer with beingignorant of their tilt angles. Accordingly, a remedy and an improvementfor the drawbacks resulted by the tilt angles could not be implemented.Worse still, the magnetic head may be abandoned due to the severe tiltangle.

Hence, it is desired to provide a measuring method of a magnetic head tomeasure out the above-mentioned tilt angles, so as to overcome thedrawbacks mentioned-above.

SUMMARY OF THE INVENTION

One objective of the present invention is to provide a measuring methodof a magnetic head, which can calculate the pinned direction tilt angleof the pinned layer that the actual pinned direction tilts towards thenormal pinned direction; moreover, the measuring method is easy tooperate, and the measuring result is accurate.

Accordingly, another objective of the present invention is to provide ameasuring method of a magnetic head, which can calculate the actualpinned direction tilt angle of the pinned layer that the actual pinneddirection tilts towards the normal pinned direction, and themagnetization direction tilt angle of the free layer that the actualmagnetization direction tilts from the actual pinned direction.

Accordingly, yet an objective of the present invention is to provide ameasuring apparatus of a magnetic head, which can calculate the pinneddirection tilt angle of the pinned layer that the actual pinneddirection tilts towards the normal pinned direction; moreover, themeasuring method is easy to operate, and the measuring result isaccurate.

To achieve the above objectives, a measuring method of a magnetic headof the present invention, includes steps of:

(a) placing the magnetic head at normal position, defining a firstdirection parallel to an ABS and two shielding layers of the magnetichead, and defining a second direction perpendicular to the ABS;

(b) tilting the magnetic head at an angle to the second direction,applying a plurality of first magnetic fields with different intensitiesin the first direction to the magnetic head, and measuring out a firstoutput parameter curve;

(c) repeating the step (b) with different angles and measuring out aplurality of first output parameter curves;

(d) calculating a plurality of pinned direction tilt ratios that apinned direction of a pinned layer of the magnetic head tilts towardsthe second direction according to the first output parameter curves; and

(e) calculating a pinned direction tilt angle that the pinned directiontilts towards the second direction according to the pinned directiontilting ratios.

As a preferred embodiment, applying a plurality of first magnetic fieldswith different intensities in the first direction to the magnetic headin the step (b) further comprises sub-steps of:

(b1) gradually applying the first magnetic field from 0 Oe to +15 kOe,thereby obtaining a first curve portion of the first output parametercurve;

(b2) gradually applying the first magnetic field from +15 kOe to 0 Oe,thereby obtaining a second curve portion of the first output parametercurve;

(b3) gradually applying the first magnetic field from 0 Oe to −15 kOe,thereby obtaining a third curve portion of the first output parametercurve; and

(b4) gradually applying the first magnetic field from −15 kOe to 0 Oe,thereby obtaining a fourth curve portion of the first output parametercurve.

Preferably, the step (d) further includes detecting a pair of outputamplitudes at symmetrical coordinates on the first output parametercurve, and detecting the minimal output amplitude on the first outputparameter curve so as to calculate the pinned direction tilting ratio.

Preferably, the step (d) further includes detecting the pair of outputamplitudes on the second curve portion and the fourth curve portion ofthe first output parameter curve at symmetrical coordinates.

Preferably, the step (d) further includes detecting the pair of outputamplitudes on the first output parameter curve under the first magneticfield with intensities of −1.5 kOe and +1.5 kOe respectively.

Preferably, the step (d) further includes detecting the pair of outputamplitudes on the first output parameter curve under the magnetic fieldwith intensities of −1 kOe and +1 kOe respectively.

Preferably, the angle in the steps (b) and (c) has a range of −80°˜+90°.

As another embodiment, after the step (e), the method further includessteps of:

(f) titling the magnetic head to make the pinned direction parallel tothe first direction, applying a plurality of second magnetic fields withdifferent intensities in the first direction to the magnetic head, andmeasuring out a second output parameter curve;

(g) detecting several maximum output amplitudes on the second outputparameter curve so as to calculate a magnetization direction tilt ratioof a magnetization direction of a free layer of the magnetic headtitling towards the pinned direction; and

(h) calculating a magnetization direction tilt angle that themagnetization direction tilts towards the pinned direction according tothe magnetization direction tilt ratio.

Preferably, applying a plurality of second magnetic fields withdifferent intensities in the first direction to the magnetic head in thestep (f) further includes sub-steps of:

(f1) gradually applying the second magnetic field from 0 Oe to +15 kOe,thereby obtaining a first curve portion of the second output parametercurve;

(f2) gradually applying the second magnetic field from +15 kOe to 0 Oe,thereby obtaining a second curve portion of the second output parametercurve;

(f3) gradually applying the second magnetic field from 0 Oe to −15 kOe,thereby obtaining a third curve portion of the second output parametercurve; and

(f4) gradually applying the second magnetic field from −15 kOe to 0 Oe,thereby obtaining a fourth curve portion of the second output parametercurve.

Preferably, the step (g) further includes detecting a first maximumoutput amplitude on the first and second curve portions of the secondoutput parameter curve, and detecting a second maximum output amplitudeon the third and fourth curve portions of the second output parametercurve.

Accordingly, a measuring apparatus of a magnetic head of the presentinvention includes an adjustment device for tilting the magnetic head atan angle to a second direction that is perpendicular to an ABS of themagnetic head; a magnetic field applying device for applying a pluralityof first magnetic fields with different intensities in a first directionto the magnetic head, and the first direction parallel to the ABS andtwo shielding layers of the magnetic head; a measuring device formeasuring out first output parameter curves with the first magneticfields applying; and an calculation device for calculating pinneddirection tilt ratios that a pinned direction of a pinned layer of themagnetic head tilts towards the second direction according to the firstoutput parameter curves, and calculating a pinned direction tilt anglethat the pinned direction tilts towards the second direction accordingto the pinned direction tilting ratios.

In comparison with the prior art, the present invention can calculatethe pinned direction tilt angle of the pinned layer that the actualpinned direction tilts towards the second direction (the normal pinneddirection), and calculate the magnetization direction tilt angle of thefree layer that the actual magnetization direction tilts towards theactual pinned direction. Thus the manufacturers can understand theperformance of the magnetic head according to the tilt angles, and tryto improve the bad performance before the product into the market.Therefore the measuring method of the present invention is quite desiredby the manufacturers.

Other aspects, features, and advantages of this invention will becomeapparent from the following detailed description when taken inconjunction with the accompanying drawings, which are a part of thisdisclosure and which illustrate, by way of example, principles of thisinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings facilitate an understanding of the variousembodiments of this invention. In such drawings:

FIG. 1 is a perspective view of a conventional magnetic head;

FIG. 2 a is a cross section view of a read head of the magnetic headshown in FIG. 1;

FIG. 2 b is a schematic diagram that shows the actual pinned directionof a pinned layer of the read head and the actual magnetizationdirection of a free layer of the read head shown in FIG. 2 a;

FIG. 3 is a perspective view of a magnetic head according to the presentinvention;

FIG. 4 is a perspective view of a read head of the magnetic head shownin FIG. 3;

FIG. 5 is a flowchart of measuring method of a magnetic head accordingto one embodiment of the present invention;

FIG. 6 is a flowchart of measuring method of a magnetic head accordingto another preferable embodiment of the present invention;

FIGS. 7 a-7 i and FIGS. 8 a-8 i show measuring graphs for a firstmagnetic head sample according to a first embodiment;

FIG. 9 is a graph that all the pinned direction tilt ratios are plottedthereon according to the first embodiment;

FIG. 9 a shows a first tilting status of the pinned direction tiltratio;

FIG. 9 b shows a second tilting status of the pinned direction tiltratio;

FIG. 9 c shows a third tilting status of the pinned direction tiltratio;

FIG. 9 d shows an actual tilting status of the pinned direction tiltratio according to the first embodiment;

FIG. 10 shows a response curve of the magnetic head that the pinneddirection is tilted parallel to the first direction according to thefirst embodiment;

FIG. 11 shows the tilting status of the actual pinned direction and theactual magnetization direction according to the first embodiment;

FIGS. 12 a-12 h show a part of measuring graphs for a second magnetichead sample according to a second embodiment;

FIG. 12 i is a graph that all the pined direction tilt ratios areplotted thereon according to the second embodiment;

FIG. 12 j shows a response curve of the magnetic head that the pinneddirection is tilted parallel to the first direction according to thesecond embodiment;

FIG. 12 k shows the tilting status of the actual pinned direction andthe actual magnetization direction according to the second embodiment;

FIGS. 13 a-13 h show measuring graphs of a third example for a thirdmagnetic head sample;

FIG. 13 i is a graph that all the pined direction tilt ratios areplotted thereon according to the third example;

FIG. 13 j shows a response curve of the magnetic head that the pinneddirection is tilted parallel to the first direction according to thethird embodiment;

FIG. 13 k shows the tilting status of the actual pinned direction andthe actual magnetization direction according to the third embodiment;and

FIG. 14 is a structure diagram of a measuring apparatus of a magnetichead according to one embodiment of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATED EMBODIMENTS

Various preferred embodiments of the invention will now be describedwith reference to the figures, wherein like reference numerals designatesimilar parts throughout the various views. As indicated above, theinvention is directed to a measuring method of a magnetic head, whichcan calculate the actual pining direction tilt angle of the pinneddirection of the pinned layer tilting towards a normal direction;moreover, the measuring method is easy to operate, and the measuringresult is accurate.

In this invention, the present description only concentrates on theembodiment of the CPP-TMR read head. But the invention is not limited tothis type of read head, any MR read head including pinned layer and freelayer can be tested by the measuring method of the present invention bythe persons ordinarily skilled in the art.

Referring to FIG. 3, the magnetic head 300 of the invention includes asubstrate body 301, an ABS 302 and a bottom surface (not shown) oppositeto the ABS 302, a trailing edge 303 and a trailing edge (not shown)opposite each other. A read head 310 and a write head 320 is embedded inthe trailing edge 303, and As shown in FIG. 4, the read head 310includes two shielding layer 311, 312 and a MR element 330 sandwichedtherebetween and having a pinning (or an AFM) layer 336, and twosynthetic pinned layers 331 and 334, a tunnel barrier layer 335 and afree layer 337. A pair of hard magnet layers 338 is placed at two sidesof the MR element 330.

The actual pinned direction of the pinned layer 331 and the actuamagnetization direction of the free layer 337 will be measured by thefollowing description. For the best illustration, only the pinneddirection and the magnetization direction will be shown in the followingdescription.

FIG. 5 is a flowchart of measuring method of a magnetic head accordingto one embodiment of the present invention, which includes:

Step (51) placing the magnetic head at normal position, and defining afirst direction parallel to the ABS and the two shielding layers and asecond direction perpendicular to ABS;

Step (52) tilting the magnetic head at an angle to the second direction,applying a plurality of first magnetic fields with different intensitiesin the first direction to the magnetic head, and measuring out a firstoutput parameter curve;

step (53) repeating the step (52) with different angles and measuringout a plurality of first output parameter curves;

step (54) calculating a plurality of pinned direction tilt ratios thatthe pinned direction tilts towards the second direction according to thefirst output parameter curves; and

step (55) calculating the pinned direction tilt angle that the pinneddirection tilts towards the second direction according to the pinneddirection tilting ratios.

By combining with FIGS. 3-5, the normal position of the magnetic head300 in the present invention is the position that ABS 302 of themagnetic head 300 is parallel to the horizontal, that is, the substratebody 301 is parallel to the horizontal and has no tilting towards thehorizontal. As shown in FIGS. 3-4, the first direction 12 is parallel tothe ABS 302 and the two shielding layers 311, 312, and the seconddirection 13 is perpendicular to the first direction 12 and ABS 302, thesecond direction 13 corresponds to the normal pinned direction.

Specifically, the angle in the steps (52) and (53) has a range of−80°˜+90°. In the present invention, eighteen measuring times for onemagnetic head sample is carried out within the above angle range so asto ensure the measuring precision, for example at angles −80°, −70°, . .. , −20°, −10°, 0, +10°, +20°, . . . , +70°, +80°, +90° respectively.The measuring times are not limited in the present invention of course.

Preferably, the intensities of the first magnetic field applied at everymeasuring time has a range of −15 kOe˜15 kOe. It should be noticed that,the magnetic field with positive number has an opposite direction to themagnetic field with negative number, which is known to personsordinarily skilled in the art. Concretely, the first output parametercurve in the step (52) is measured out by applying the different firstmagnetic fields for a cycle with four times. More concretely, thesub-steps include gradually applying the first magnetic field from 0 Oeto 15 kOe, thereby obtaining a first curve portion of the first outputparameter curve; gradually applying the first magnetic field from 15 kOeto 0 Oe, thereby obtaining a second curve portion of the first outputparameter curve; gradually applying the first magnetic field from 0 Oeto −15 kOe, thereby obtaining a third curve portion of the first outputparameter curve; and gradually applying the first magnetic field from−15 kOe to 0 Oe, thereby obtaining a fourth curve portion of the firstoutput parameter curve.

As an essential of the present invention, the pinned direction tiltratios in the step (54) is calculated by detecting a pair of outputamplitudes at symmetrical coordinates, and a minimal output amplitude onthe first output parameter curve and computing by a formula. It'spreferable to select the pair of output amplitudes on the first outputparameter curve under the magnetic field with intensities of −1.5 kOeand 1.5 kOe respectively or −1.0 kOe and 1.0 kOe respectively. Morepreferably, the pair of output amplitudes is selected on the secondcurve portion and the fourth curve portion of the first output parametercurve at symmetrical coordinates.

Within the contemplation of the present invention, the magnetizationdirection tilt angle of the free layer that tilts towards the pinneddirection can be measured out basing on the pinned direction tilt anglemeasured out.

FIG. 6 is a flowchart of measuring method of a magnetic head accordingto another preferable embodiment of the present invention, whichincludes:

Step (61) placing the magnetic head at normal position, and defining afirst direction parallel to the ABS and the two shielding layers and asecond direction perpendicular to the first direction;

Step (62) tilting the magnetic head at an angle to the second direction,applying a plurality of first magnetic fields with different intensitiesin the first direction to the magnetic head, and measuring out a firstoutput parameter curve;

step (63) repeating the step (62) with different angles and measuringout a plurality of first output parameter curves;

step (64) calculating a plurality of pinned direction tilt ratios thatthe pinned direction tilts towards the second direction according to thefirst output parameter curves;

step (65) calculating the pinned direction tilt angle that the pinneddirection tilts towards the second direction according to the pinneddirection tilting ratios;

step (66) titling the magnetic head to make the pinned directionparallel to the first direction, applying a plurality of second magneticfields with different intensities in the first direction to the magnetichead, and measuring out a second output parameter curve; concretely, thepinned direction can be tilted to the same to the first direction, oropposite to the first direction.

step (67) detecting several maximum amplitudes on the second outputparameter curve so as to calculate a magnetization direction tilt ratioof the magnetization direction titling towards the pinned direction; and

step (68) calculating a magnetization direction tilt angle that themagnetization direction tilts towards the pinned direction according tothe magnetization direction tilt ratio.

Similarly to the first embodiment, the range of the intensities of thesecond magnetic field is −15 kOe˜15 kOe as well. Concretely, the secondoutput parameter curve in the step (66) is measured out by applying thedifferent second magnetic fields for a cycle with four times. Moreconcretely, the sub-steps include gradually applying the second magneticfield from 0 Oe to 15 kOe, thereby obtaining a first curve portion ofthe second output parameter curve; gradually applying the secondmagnetic field from 15 kOe to 0 Oe, thereby obtaining a second curveportion of the second output parameter curve; gradually applying thesecond magnetic field from 0 Oe to −15 kOe, thereby obtaining a thirdcurve portion of the second output parameter curve; and graduallyapplying the second magnetic field from −15 kOe to 0 Oe, therebyobtaining a fourth curve portion of the second output parameter curve.

Specifically, the first maximum output amplitude is detected on thefirst and the second curve portions, and the second maximum outputamplitude is detected on the third and fourth curve portions, and themagnetization direction tilt ratio of the magnetization directiontilting towards the pinned direction can be calculated according to thetwo output amplitudes, and then the magnetization direction tilt anglecan be calculated according to the magnetization direction tilt ratiowhich is known to person ordinarily skilled in the art.

Now the detailed invention concepts will be explained specifically bycombining with several measurement experimentation examples. In thefollowing examples, the output parameter of the first and second outputparameter curves is indicated by output voltage; it also can beindicated by output resistance, of course.

FIGS. 7 a-7 i and FIGS. 8 a-8 i show measuring graphs for a firstmagnetic head sample according to a first embodiment. As mentionedabove, the magnetic head sample is measured by eighteen times under tiltangles of −80°, −70°, −20°, −10°, 0, +10°, +20°, . . . , +70°, +80°,+90° respectively. Every first output parameter curve is obtained byapplying the first magnetic field according to four sub-steps explainedabove, and the first output parameter curve includes first, second,third and fourth curve portions (not labeled).

And then, a plurality of pinned direction tilt ratios is calculatedaccording to these curves. As shown in FIG. 7 a for example, the minimaloutput amplitude on the first output parameter curve is detected andlabeled by Min1, and the two output amplitudes are detected under theY-coordinate is −1.5 kOe and 1.5 kOe and labeled by V1, V2, and thepinned direction tilt ratio can be calculated by the below equation:

${T = \frac{\left( {{V\; 1} - {{Min}\; 1}} \right) - \left( {{V\; 2} - {{Min}\; 1}} \right)}{\left( {{V\; 1} + {{Min}\; 1}} \right) + \left( {{V\; 2} + {{Min}\; 1}} \right)}};$

Similarly, all the pined direction tilt ratios of the graphs arecalculated by the above method which are not shown in every graph. FIG.9 is a graph that all the pined direction tilt ratios are plottedthereon.

Within the contemplation of the present invention, if the pinneddirection tilt ratio is equal to Zero, the actual pinned direction 354′has no offset to the normal pinned direction 354, namely the actualpinned direction 354′ is perpendicular to the first direction 12 shownin FIG. 9 a and FIG. 4; if the pinned direction tilt ratio is smallerthan Zero, the actual pinned direction 354′ tilts towards one side ofthe normal pinned direction 354 at a negative angle as shown in FIG. 9 band FIG. 4; if the pinned direction tilt ratio is larger than Zero, theactual pinned direction 354′ tilts towards another side of the normalpinned direction 354 at a positive angle as shown in FIG. 9 c and FIG.4, which is easy to be understood by persons ordinarily skilled in theart.

Basing on the above concept, the actual pinned direction tilt angle canbe calculated in the curve shown in FIG. 9. The X-intercept on theX-axis of the curve will be estimated, which is the actual pinneddirection tilt angle. It can be seen that, the actual pinned directiontilt angle A1 of the present embodiment is equal to −10°, which thetilting status of the actual pinned direction 354′ is shown in FIG. 9 d.

Now the actual magnetization direction tilt angle of the free layer willbe measured based on the actual pinned direction tilt angle A1=−10°. Themagnetic head is tilted to make the actual pinned direction parallel tothe first direction, concretely opposite to the first direction in thisembodiment. Then gradually apply a second magnetic field in the firstdirection from 0 Oe to 15 kOe, 15 kOe to 0 Oe, 0 Oe to −15 kOe, −15 kOeto 0 Oe respectively, and detect the response curve of the magnetic headwith four curve portions as shown in FIG. 10. The maximum outputamplitude Max1 under the positive magnetic field is detected, and themaximum output amplitude Max2 under the negative magnetic field isdetected, and the magnetization direction tilt ratio is calculated bythe below equation:

${T = \frac{{{Max}\; 1} - {{Max}\; 2}}{{{Max}\; 1} + {{Max}\; 2}}};$

Thus in the present embodiment,

${T = {\frac{37 - 14}{37 + 14} = 0.45}},$accordingly, the magnetization direction tilt angle A1′ that the actualmagnetization direction 356′ tilts towards the actual pinned direction354′ is calculated. After the estimation, the magnetization directiontilt angle A1′=64°.

In conclusion, the actual pinned direction tilt angle A1 and the actualmagnetization direction tilt angle A1′ in this embodiment is illustratedin FIG. 11.

FIGS. 12 a-12 h show a part of measuring graphs of for a second magnetichead sample according to a second embodiment, only several typicalmeasuring graph are shown. The measuring method is the same to the firstembodiment, whose detailed explanations are omitted here. The actualpinned direction tilt angle A2=+20° estimated by curve tracing in FIG.12 i. And the magnetization direction tilt ratio T2′=0.24 calculatedaccording to the response curve shown in FIG. 12 j, and themagnetization direction tilt angle A2′=76°. The actual pinned directiontilt angle A2 and the actual magnetization direction tilt angle A2′ inthis embodiment is illustrated in FIG. 12 k.

FIGS. 13 a-13 h show a part of measuring graphs for a third magnetichead sample according to a third embodiment. The measuring method forthe pinned direction tilt angle is similar to the first embodiment,except that the two output amplitudes V1, V2 are detected under theX-axis is −1 kOe and +1 kOe when measuring the pinned direction tiltratios, as shown in FIG. 13 a for example. FIG. 13 i shows all pinneddirection tilt ratios measured for eighteen times, and the actual pinneddirection tilt angle A3 of the present magnetic head is equal to +50°.And the magnetization direction tilt angle T3′=−0.33 according to theresponse curve in FIG. 13 j, thus the magnetization direction tilt angleA3′=110°. Therefore, the actual pinned direction tilt angle A3 and theactual magnetization direction tilt angle A3′ in this embodiment isillustrated in FIG. 13 k.

A plurality of magnetic head samples is tested by the present measuringmethod, only three representative examples are shown in the aboveembodiments.

In comparison with the prior art, the present invention can measure outthe pinned direction tilt angle of the pinned layer that the actualpinned direction tilts towards the second direction (the normal pinneddirection), and measure out the magnetization direction tilt angle ofthe free layer that the actual magnetization direction tilts towards theactual pinned direction. Thus the manufacturers can understand theperformance of the magnetic head according to the tilt angles, and tryto improve the bad performance before the product into the market.Therefore the measuring method of the present invention is quite desiredby the manufacturers.

Accordingly, the present invention also provides a measuring apparatus800 of a magnetic head, as shown in FIG. 14. The measuring apparatus 800is adapted for performing the measuring method described above, whichincludes an adjustment device 801 for tilting the magnetic head at anangle to a second direction that is perpendicular to an ABS of themagnetic head; a magnetic field applying device 802 for applying aplurality of first magnetic fields with different intensities in a firstdirection to the magnetic head, and the first direction parallel to theABS and two shielding layers of the magnetic head; a measuring device803 for measuring out first output parameter curves with the firstmagnetic fields applying; and an calculation device 804 for calculatingpinned direction tilt ratios that a pinned direction of a pinned layerof the magnetic head tilts towards the second direction according to thefirst output parameter curves, and calculating a pinned direction tiltangle that the pinned direction tilts towards the second directionaccording to the pinned direction tilting ratios.

Preferably, the adjustment device 801 is further arranged for tiltingthe magnetic head to make the pinned directing parallel to the firstdirection, the magnetic field applying device 802 is further arrangedfor applying a plurality of second magnetic fields with differentintensities in the first direction to the magnetic head, the measuringdevice 803 is further arranged for measuring out second output parametercurves with the second magnetic fields applying, and the calculationdevice 804 is further arranged for calculating a magnetization directiontilt ratio of a magnetization direction of the free layer of themagnetic head titling towards the pinned direction.

It's easy to understand that the measuring apparatus 800 performs thecorresponding process mentioned above and can obtain all advantagesdescribed in the embodiments of the measuring method.

While the invention has been described in connection with what arepresently considered to be the most practical and preferred embodiments,it is to be understood that the invention is not to be limited to thedisclosed embodiments, but on the contrary, is intended to cover variousmodifications and equivalent arrangements included within the spirit andscope of the invention.

What is claimed is:
 1. A measuring method of a magnetic head, comprisingsteps of: (a) placing the magnetic head at normal position, defining afirst direction parallel to an air bearing surface and two shieldinglayers of the magnetic head, and defining a second directionperpendicular to air bearing surface; (b) tilting the magnetic head atan angle to the second direction, applying a plurality of first magneticfields with different intensities in the first direction to the magnetichead, and measuring out a first output parameter curve; (c) repeatingthe step (b) with different angles and measuring out a plurality offirst output parameter curves; (d) calculating a plurality of pinneddirection tilt ratios that a pinned direction of a pinned layer of themagnetic head tilts towards the second direction according to the firstoutput parameter curves; and (e) calculating a pinned direction tiltangle that the pinned direction tilts towards the second directionaccording to the pinned direction tilting ratios.
 2. The measuringmethod according to claim 1, wherein the step (b) further comprisessub-steps of: (b1) gradually applying the first magnetic field from 0 Oeto +15 kOe, thereby obtaining a first curve portion of the first outputparameter curve; (b2) gradually applying the first magnetic field from+15 kOe to 0 Oe, thereby obtaining a second curve portion of the firstoutput parameter curve; (b3) gradually applying the first magnetic fieldfrom 0 Oe to −15 kOe, thereby obtaining a third curve portion of thefirst output parameter curve; and (b4) gradually applying the firstmagnetic field from −15 kOe to 0 Oe, thereby obtaining a fourth curveportion of the first output parameter curve.
 3. The measuring methodaccording to claim 2, wherein the step (d) further comprises detecting apair of output amplitudes at symmetrical coordinates on the first outputparameter curve, and detecting a minimal output amplitude on the firstoutput parameter curve so as to calculate the pinned direction tiltingratio.
 4. The measuring method according to claim 3, wherein the step(d) further comprises detecting the pair of output amplitudes on thesecond curve portion and the fourth curve portion of the first outputparameter curve at symmetrical coordinates.
 5. The measuring methodaccording to claim 3, wherein the step (d) further comprises detectingthe pair of output amplitudes on the first output parameter curve underthe first magnetic field with intensities of −1.5 kOe and +1.5 kOerespectively.
 6. The measuring method according to claim 3, wherein thestep (d) further comprises detecting the pair of output amplitudes onthe first output parameter curve under the first magnetic field withintensities of −1 kOe and +1 kOe respectively.
 7. The measuring methodaccording to claim 1, wherein the step (e) further comprises calculatingthe pinned direction tilting angle by curve tracing.
 8. The measuringmethod according to claim 1, wherein the angle in the steps (b) and (c)has a range of −80°˜+90°.
 9. The measuring method according to claim 1,wherein after the step (e), the method further comprises steps of: (f)titling the magnetic head to make the pinned direction parallel to thefirst direction, applying a plurality of second magnetic fields withdifferent intensities in the first direction to the magnetic head, andmeasuring out a second output parameter curve; (g) detecting severalmaximum output amplitudes on the second output parameter curve so as tocalculate a magnetization direction tilt ratio of a magnetizationdirection of a free layer of the magnetic head titling towards thepinned direction; and (h) calculating a magnetization direction tiltangle that the magnetization direction tilts towards the pinneddirection according to the magnetization direction tilt ratio.
 10. Themeasuring method according to claim 9, wherein the step (f) furthercomprises titling the magnetic head to make the pinned direction same tothe first direction.
 11. The measuring method according to claim 9,wherein the step (f) further comprises titling the magnetic head to makethe pinned direction opposite to the first direction.
 12. The measuringmethod according to claim 9, wherein the step (f) further comprisessub-steps of: (f1) gradually applying the second magnetic field from 0Oe to +15 kOe, thereby obtaining a first curve portion of the secondoutput parameter curve; (f2) gradually applying the second magneticfield from +15 kOe to 0 Oe, thereby obtaining a second curve portion ofthe second output parameter curve; (f3) gradually applying the secondmagnetic field from 0 Oe to −15 kOe, thereby obtaining a third curveportion of the second output parameter curve; and (f4) graduallyapplying the second magnetic field from −15 kOe to 0 Oe, therebyobtaining a fourth curve portion of the second output parameter curve.13. The measuring method according to claim 12, wherein the step (g)further comprising detecting a first maximum output amplitude on thefirst and second curve portions of the second output parameter curve,and detecting a second maximum output amplitude on the third and fourthcurve portions of the second output parameter curve.
 14. The measuringmethod according to claim 9, wherein the intensities of the first andsecond magnetic fields have a range of −15 kOe˜+15 kOe.
 15. Themeasuring method according to claim 9, wherein the output parameter ofthe first and the second output parameter curves is output resistance oroutput voltage.
 16. A measuring apparatus of a magnetic head,comprising: an adjustment device for tilting the magnetic head at anangle to a second direction that is perpendicular to an air bearingsurface of the magnetic head; a magnetic field applying device forapplying a plurality of first magnetic fields with different intensitiesin a first direction to the magnetic head, and the first directionparallel to the air bearing surface and two shielding layers of themagnetic head; a measuring device for measuring out first outputparameter curves with the first magnetic fields applying; and ancalculation device for calculating pinned direction tilt ratios that apinned direction of a pinned layer of the magnetic head tilts towardsthe second direction according to the first output parameter curves, andcalculating a pinned direction tilt angle that the pinned directiontilts towards the second direction according to the pinned directiontilting ratios.
 17. The measuring apparatus according to claim 16,wherein the calculation device is further arranged for detecting a pairof output amplitudes at symmetrical coordinates, and a minimal outputamplitude on the first output parameter curve so as to calculate thepinned direction tilting ratio.
 18. The measuring apparatus according toclaim 16, wherein the adjustment device is further arranged for tiltingthe magnetic head to make the pinned directing parallel to the firstdirection.
 19. The measuring apparatus according to claim 18, whereinthe magnetic field applying device is further arranged for applying aplurality of second magnetic fields with different intensities in thefirst direction to the magnetic head.
 20. The measuring apparatusaccording to claim 19, wherein the measuring device is further arrangedfor measuring out a second output parameter curve with the secondmagnetic fields applying.
 21. The measuring apparatus according to claim20, wherein the calculation device is further arranged for calculating amagnetization direction tilt ratio of a magnetization direction of afree layer of the magnetic head titling towards the pinned directionaccording to the second output parameter curve.
 22. The measuringapparatus according to claim 21, wherein the calculation device isfurther arranged for detecting several maximum amplitudes on the secondoutput parameter curve so as to calculate the magnetization directiontilt ratio.
 23. The measuring apparatus according to claim 22, whereinthe calculation device is further arranged for calculating amagnetization direction tilt angle that the magnetization directiontilts towards the pinned direction according to the magnetizationdirection tilt ratio.
 24. The measuring apparatus according to claim 19,wherein the intensities of the first and second magnetic fields have arange of −15 kOe˜+15 kOe.
 25. The measuring apparatus according to claim16, wherein the adjustment device is arranged for tilting the magnetichead at an angle with a range of −80°˜+90° to the second direction.